One step dual foam crash pad mold assembly

ABSTRACT

The instant invention relates to a mold and a method used therewith for manufacturing multi-density foamed articles such as dual foam crash pads of the type used in automobiles in a one step operation which includes providing divider means disposed in a mold cavity for dividing the mold cavity into at least two sections whereby a first foamable material may be injected into a first section while substantially simultaneously injecting a second foamable material into a second section.

United States Patent 1191 Rhodes, Jr.

[ 1 Nov. 11, 1975 1 ONE STEP DUAL FOAM CRASH PAD MOLD ASSEMBLY [75]Inventor: Richard D. Rhodes, Jr.,

Somersworth, NH.

[73] Assignee: McCord Corporation, Detroit,

Mich.

[22] Filed: Apr. 17, 1974 [21} Appl No.: 461,742

Related US. Application Data [62] Division of Ser. No. 244,502. April17. 1972, Pat.

[52] US. Cl. 425/117; 249/83 [51] Int. Cl. B29C 1/00 [58] Field ofSearch 425/117, 110, 817, 4, 120;

[56] References Cited UNITED STATES PATENTS 3.074.112 1/1963 Bobrow v.249/83 3.392.685 7/1968 Briggs 249/129 3.782.678 1/1974 Thams 249/129FOREIGN PATENTS OR APPLICATIONS 192.550 10/1957 Austria' 249/84 PrimaryExaminerDonald G. Kelly Assistant Iivanzincr-Margaret Joyce Attorney,Age/1i, 0r FirmMCGlynn and Milton [5 7 ABSTRACT The instant inventionrelates to a mold and a method used therewith for manufacturingmulti-density foamed articles such as dual foam crash pads of the typeused in automobiles in a one step operation which includes providingdivider means disposed in a mold cavity for dividing the mold cavityinto at least two sections whereby a first foamable material may beinjected into a first section while substantially simultaneouslyinjecting a second fo'amable material into a second section.

7 Claims, 1 Drawing Figure US. Patent Nov. 11, 1975 3,918,863

This application is a divisionalof Application Ser.

No. 244,502, filed Apr. 17, 1972, now.U.S. Pat. No. 3,840,627 grantedOct. 8, 1974.

In recent years multi-density foamed articles have become widely used.Energy absorbing devices for example, such as foam crash pads for theprotection of automobile passengers have been developed which include anouter shell portion and an inner core portion wherein the core portionis made of a more rigid i.e., firmer or stiffer, material than the outershell portion. This dual foam structure affords better protection frominjury because the soft outer shell softens the blow while the innercore is sufficiently resilient to absorb substantial energy.

Heretofore the manufacture of multi-density foamed articles required aplurality of steps, that is the outer shell was formed with a cavitydisposed therein to receive a prefoamed inner core which was inserted'into the cavity of the shell or an inner core was foamed within thecavity. Other methods are available, of course, but in all cases aseries of operations or steps are required to form a multi-densityarticle, thereby increasing the cost and inefficiency of themanufacturing operation.

It is therefore an object and feature of the instant invention toprovide a mold assembly of the type used to manufacture multi-densityfoamed articles comprising divider means disposed within a mold cavityfor dividing the mold cavity into at least two sections and passagemeans in communication with each of the sections whereby foamablematerials may be injected substantially simultaneously into each of saidsections.

It is another object and feature of the instant invention to provide amethod for manufacturing a multidensity foamed article in substantiallya one step operation, that is, once the mold has been prepared andclosed the foamable materials are substantially simultaneously injectedand a multi-density article results. I

In correlation with the foregoing object and feature, it is anotherobject and feature of the instant invention to provide a method formanufacturing multi-density foamed article which comprises the steps ofinjecting a first foamable material into a first section divided from asecond section by divider means while substantially simultaneouslyinjecting a second foamable material into a second section and foamingand curing the first and second foamable materials whereby the firstsection is adapted to be comprised of a foamed material ofsubstantially, different physical characteristics than the secondsection.

Other objects and attendant advantages of the instant invention will bereadily appreciated as the same becomes better understood by referenceto the following detailed description when considered in connection withthe accompanying drawings wherein:

The FIGURE is a cross-sectional view of a multidensity foam crash padmanufactured in accordance with the method of the instant invention.

Referring to the drawing, a mold assembly is generally indicated at 10.A mold cavity is defined by a female body member 12 and a cover member14. The mold assembly is understood to include any standard clampingmeans (not shown) for holding and sealing the cover member 14 to thebody member 12.

Within the. moldcavity and temporarily secured to the cover member 14 isa divider means 16. The divider means 16 separates the mold cavity intotwo sections,

an inner or core section 18 and an outer or shell section 20.

The divider means 16 can be made of a variety of-thin materials such aspaper, cardboard, or polystyrene which will define the desired shape ofthe core section 18. Preferably the divider means 16 is a flexiblemembrane, although it may be'rigid.

The mold cover 14 includes pour hole or passage 22 which is incommunication with the inner or core section 18 and apour hole orpassage 24 which is in communication with the outer or shell section 20.

When the mold cover 14 is clamped in place with the divider means 16held thereto within the mold cavity to define the core and shellsections 18 and 20, the mold assembly is ready to receive a foamedmaterial. A first foamable material is injected from injection nozzle 26into the core section 18 through pour hole 22 and a second foamablematerial is injected from injection nozzle 28 into the shell sectionthrough pour hole The outer or shell section 20 may be foamed'fromanyone of a number of foamable materials or resins which areself-skinning to produce a skin or decorative cover 30 around theexternal surface of the multidensity foam crash pad; however, this isnot required for the satisfactory performance of the crash pad.Alternatively, a sheet of plastic type material may be disposed againstthe wall of the shell section 20 of the cavity before injecting thefoamable material to provide the skin or decorative cover.

The physical properties of the two foamable materials are different sothat when the materials have foamed and cured in the usual manner thedensity of the core section 18 will be different from that of the shellsection 20. In the case of crash pads for automobiles the foamablematerials are selected and injected so that the core section 18 will bemore dense or firmer than the shell section 20. In other words, theshell section 20 will be softer and more resilient than the core section18.

The injection operation is timed so that as the foamable materials foamand fill the two sections of the mold cavity the divider means 16 willnot be distorted but will maintain its original desired shape. Thetiming of the two shots of foamable material would depend on thereactivity of each material used and would yield a multi-density foamcrash pad with the core section 18 having the same dimensions as definedby the divider means 16. In other words, the foamable materials expandat a rate which causes no significant distortion or change in theposition of the divider means 16.

The foamable materials having been foamed are allowed to cure as is the'normal practice. The multidensity foam crash pad is then removed fromthe mold cavity; the divider means 16 remain an integral part thereof.It is to be understood that the divider means 16 may be selected for itscontributory physical properties; that is, the thickness, composition,or design may be varied to allow it to contribute to the energyabsorbing characteristics of the crash pad.

The method is not restricted to dual foam crash pads or articles becauseit is obvious that additional divider means and pour holes may beprovided so that three or four layers of foamed material may beproduced.

By the method and provisions thereof set forth in the precedingdescription, a method for manufacturing a multi-density foam article andin particular a multidensity foam crash pad has been disclosed.

While a novel method and mold assembly for manufacturing a specific formof a multi-density foamed article have been illustrated and described inthe foregoing specification and accompanying drawings, it should beunderstood that the invention is not limited to the exact method andassembly shown but that various alternatives in the construction andarrangement of parts as well as the steps of the method will becomeapparent to those skilled in the art without departing from the scopeand spirit of the invention which is defined by the claims which follow.

I claim:

1. A mold assembly of the type used to manufacture multi-density foamedarticles comprising; a body member and a cover member defining a moldcavity, said members being movable between open and closed positions foropening and closing said cavity, a nondistortable sheet disposed withinsaid mold cavity for dividing said mold cavity into at least twosections, said sheet being removably attached to one of said members forbeing removed from said mold cavity with a foamed article, said sheetbeing suspended from its extremities and extending centrally throughsaid cavity in spaced relationship to said members whereby said sheet issuspended within said cavity, and passage means in communication witheach of said sections whereby foamable materials may be injectedsubstantially simultaneously into each of said sections while maintainedseparated.

2. An assembly as set forth in claim 1 wherein said sheet is comprisedof a relatively flexible material 3. An assembly as set forth in claim 1wherein said sheet is comprised of a rigid material.

4. An assembly as set forth in claim 1 wherein said sheet divides saidcavity into a core section and shell section which at least in partsurrounds said core section.

5. An assembly as set forth in claim 4 wherein said shell section isgenerally U-shaped in cross section and said core section is disposedwithin said U-shape.

6. An assembly as set forth in claim 5 wherein said cover memberincludes said passage means, said passage means including at least onepassage extending therethrough and in communication with said coresection and at least one passage extending therethrough and incommunication with said shell section.

7. An assembly as set forth in claim 6 therein said cover memberincludes a protrusion extending into said core section.

1. A mold assembly of the type used to manufacture multi-density foamedarticles comprising; a body member and a cover member defining a moldcavity, said members being movable between open and closed positions foropening and closing said cavity, a nondistortable sheet disposed withinsaid mold cavity for dividing said mold cavity into at least twosections, said sheet being removably attached to one of said members forbeing removed from said mold cavity with a foamed article, said sheetbeing suspended from its extremities and extending centrally throughsaid cavity in spaced relationship to said members whereby said sheet issuspended within said cavity, and passage means in communication witheach of said sections whereby foamable materials may be injectedsubstantially simultaneously into each of said sections while maintainedseparated.
 2. An assembly as set forth in claim 1 wherein said sheet iscomprised of a relatively flexible material.
 3. An assembly as set forthin claim 1 wherein said sheet is comprised of a rigid material.
 4. Anassembly as set forth in claim 1 wherein said sheet divides said cavityinto a core section and shell section which at least in part surroundssaid core section.
 5. An assembly as set forth in claim 4 wherein saidshell section is generally U-shaped in cross section and said coresection is disposed within said U-shape.
 6. An assembly as set forth inclaim 5 wherein said cover member includes said passage means, saidpassage means including at least one passage extending therethrough andin communication with said core section and at least one passageextending therethrough and in communication with said shell section. 7.An assembly as set forth in claim 6 therein said cover member includes aprotrusion extending into said core section.